Composites composed essentially of carbon are receiving increasing attention as materials for aircraft brake discs. Innovations have depicted reinforcement of such composites by laminated carbon cloths and by continuous carbon fibers in a helical pattern about the periphery regions of the brake discs with the remaining portion of the disc containing a substantial amount of carbon fiber in continuous or staple form.
As such discs operate at high temperatures in air, oxidative deterioration at high stress areas of the peripheries has been a serious problem, limiting the usefulness of the discs. While various integral and surface permeating additives are well known to increase the oxidation resistance of carbon bodies, such additives to the complete disc may seriously detract from the desired thermal, frictional and wear characteristics of the disc when in service.
When the non-peripheral areas of discs have worn a specified amount because of friction, the disc is discarded. It would be advantageous for the users of such discs if only the worn portion of the discs could be replaced.
It is therefore a primary objective of this invention to provide a two piece brake disc comprising a modified carbon composite structural ring forming the peripheral non-wearing portion of this disc of improved oxidation resistance and an inner disc wear element of an essentially all-carbon composite comprising both friction surfaces of the disc which may be refurnished when worn.